1 . Field of the Invention
The invention relates to drilling mud control equipment, and more particularly to a weir box with a diverter plate, weir baffle plates and a sliding gate that allows drilling fluid or drilling mud to be selectively directed to a drilling mud separation unit contained therein or to bypass the separation unit prior to passing to conventional downstream solids control equipment and to selectively control and meter the flow rate and create a hydrostatic head upstream from the conventional solids control equipment.
2. Brief Description of the Prior Art
The mud system is an integral part of an oil and gas drilling rig, land or marine. Drilling mud or drilling fluid is continually recycled because of the huge cost factor and for environmental reasons. The drilling mud or drilling fluid is used to hold formation pressures in balance, to create and maintain well bore filter cake, create hydraulic horsepower at the bit, hydrostatic testing, shifting of spherical valve elements downhole, and removal of formation solids, cuttings, sand, etc., through the mud return annulus. As the drilling mud or drilling fluid flows from the bell nipple flow line its solids content is refined and removed, through a series of solids control equipment, each removing or separating the plate-like mica structure to a smaller physical size.
It is of the utmost advantage to remove as much solids as practical to reduce down time resulting from plugged flow lines, fluid end repair, drill string erosion, redrilling of the solids or sediments as the drilling mud or drilling fluid recycles itself through the mud system loop.
The conventional mechanical solids control equipment used for removing solids from drilling mud or drilling fluid involves shale shakers and vibratory screens, desilters, desanders, mud cleaners, and centrifuge. This equipment operates at different levels of particle size rejecting solids and retaining desirable solids which can be part of the drilling mud or drilling fluid additives or chemicals.
The mechanical shale shaker screens are limited to short life, and the screens become coated with sticky clays closing the pores or mesh openings resulting in fluid or mud loss. This adds to the problem as additional water must be added to the drilling mud system. This involves the addition of chemical and mud additives to restore the correct and desired mud properties and mud weight, hence the cost of drilling is increased.
The present invention overcomes the aforementioned drawbacks and disadvantages of the prior art and provides additional advantages as well.
The present invention is installed in the flow path of the drilling mud or drilling fluid in the mud system of a drilling rig, upstream of the conventional solids control equipment, and while drilling virgin or young shales it selectively separates and discharges large amounts of drill solids, gumbo, and heavy clays, from the drilling mud or drilling fluid prior to the drilling mud or drilling fluid flowing to the conventional solids control equipment or allows the separation unit to be bypassed. The present weir box employing baffle plates, a sliding gate, and selective utilization of the mud separation unit allows the operator to produce an increased hydrostatic head, which enables high flow rates to be easily processed by shale shakers and other conventional downstream solids control equipment of the mud system and to compliment the drilling operation with respect to changes in the lithology, geological formations, or loss of returns in relation to the gallons pumped or volume of drilling fluid or drilling mud entering the weir box.